Electrocardiography and respiratory monitor

ABSTRACT

A monitor recorder optimized for electrocardiography and respiratory data acquisition and processing is provided. The recorder includes a sealed housing and an electronic circuitry comprised within the sealed housing, which includes an electrocardiographic front end circuit electrically interfaced to an externally-powered micro-controller and operable to sense electrocardiographic signals through electrodes provided on the patch; the micro-controller interfaced to one or more respiratory sensors, the micro-controller operable to sample the electrocardiographic signals, to sample respiratory events detected by the one or more respiratory sensors upon receiving one or more signals from the one or more respiratory sensors, to buffer each of the respiratory event samples, to compress each of the buffered respiratory event samples, to buffer each of the compressed respiratory event samples, and to write the buffered compressed respiratory event samples and the samples of the electrocardiography signals into an externally-powered flash memory; and the memory interfaced with the micro-controller.

CROSS-REFERENCE TO RELATED APPLICATION

This non-provisional patent application is a continuation of U.S. Pat.No. 10,265,015, issued Apr. 23, 2019, which is a continuation of U.S.Pat. No. 9,955,911, issued May 1, 2018, which is a continuation of U.S.Pat. No. 9,545,228, issued Jan. 17, 2017, which is a continuation ofU.S. Pat. No. 9,364,155, issued Jun. 14, 2016, which is acontinuation-in-part of U.S. Pat. No. 9,545,204, issued Jan. 17, 2017,and which is also a continuation-in-part of U.S. Pat. No. 9,730,593,issued Aug. 15, 2017, and further claims priority under 35 U.S.C. §119(e) to U.S. Provisional Patent application, Ser. No. 61/882,403,filed Sep. 25, 2013, the disclosures of which are incorporated byreference.

FIELD

This application relates in general to electrocardiographic monitoringand, in particular, to an electrocardiography and respiratory monitor.

BACKGROUND

The heart emits electrical signals as a by-product of the propagation ofthe action potentials that trigger depolarization of heart fibers. Anelectrocardiogram (ECG) measures and records such electrical potentialsto visually depict the electrical activity of the heart over time.Conventionally, a standardized set format 12-lead configuration is usedby an ECG machine to record cardiac electrical signals fromwell-established traditional chest locations. Electrodes at the end ofeach lead are placed on the skin over the anterior thoracic region ofthe patient's body to the lower right and to the lower left of thesternum, on the left anterior chest, and on the limbs. Sensed cardiacelectrical activity is represented by PQRSTU waveforms that can beinterpreted post-ECG recordation to derive heart rate and physiology.The P-wave represents atrial electrical activity. The QRSTU componentsrepresent ventricular electrical activity.

An ECG is a tool used by physicians to diagnose heart problems and otherpotential health concerns. An ECG is a snapshot of heart function,typically recorded over 12 seconds, that can help diagnose rate andregularity of heartbeats, effect of drugs or cardiac devices, includingpacemakers and implantable cardioverter-defibrillators (ICDs), andwhether a patient has heart disease. ECGs are used in-clinic duringappointments, and, as a result, are limited to recording only thoseheart-related aspects present at the time of recording. Sporadicconditions that may not show up during a spot ECG recording requireother means to diagnose them. These disorders include fainting orsyncope; rhythm disorders, such as tachyarrhythmias andbradyarrhythmias; apneic episodes; and other cardiac and relateddisorders. Thus, an ECG only provides a partial picture and can beinsufficient for complete patient diagnosis of many cardiac disorders.

The inadequacy of conventional, short-term, ECG recordings isparticularly apparent in the case of sleep apnea, a type of sleepdisorder that affects a patient's breathing during sleep and may alsoimpact the patient's cardiac activity. ECG monitoring alone may not beuseful in diagnosing the condition due to a natural heart rate reductionduring sleep. As a patient enters non-rapid eye movement (NREM) sleep,the patient experiences physiological changes due to a withdrawal ofactivity of the patient's sympathetic nervous system. As a result, evenhealthy people may experience sinus bradyarrhythmia during sleep, andECG monitoring alone may not always reveal whether the bradyarrhythmiais naturally-occurring or is caused by a pathological condition, such asan apneic episode. Furthermore, if the patient experiences other typesof arrhythmias during sleep, without having a telemetry of the patient'sair flow, the flow of air in and out of the patient's lungs duringbreathing, or another indicator of the patient's respiration, thephysician may not be always be able to determine if an arrhythmia is aresult of a sleep apnea episode or of some other morbidity. However,considering that cardiac manifestations of sleep apnea are most apparentat night, a short-term ECG monitoring done in a clinic during businesshours may not reveal even the presence of the cardiac arrhythmia.

Diagnostic efficacy can be improved, when appropriate, through the useof long-term extended ECG monitoring coupled to pulmonary measures.Recording sufficient ECG and related physiology over an extended periodis challenging, and often essential to enabling a physician to identifyevents of potential concern. A 30-day observation period is consideredthe “gold standard” of ECG monitoring, yet achieving a 30-dayobservation day period has proven unworkable because such ECG monitoringsystems are arduous to employ, cumbersome to the patient, andexcessively costly. Ambulatory monitoring in-clinic is implausible andimpracticable. Nevertheless, if a patient's ECG and pulmonary measurescould be recorded in an ambulatory setting, thereby allowing the patientto engage in activities of daily living, the chances of acquiringmeaningful information and capturing an abnormal event while the patientis engaged in normal activities becomes more likely to be achieved.

For instance, the long-term wear of ECG electrodes is complicated byskin irritation and the inability ECG electrodes to maintain continualskin contact after a day or two. Moreover, time, dirt, moisture, andother environmental contaminants, as well as perspiration, skin oil, anddead skin cells from the patient's body, can get between an ECGelectrode, the non-conductive adhesive used to adhere the ECG electrode,and the skin's surface. All of these factors adversely affect electrodeadhesion and the quality of cardiac signal recordings. Furthermore, thephysical movements of the patient and their clothing impart variouscompressional, tensile, and torsional forces on the contact point of anECG electrode, especially over long recording times, and an inflexiblyfastened ECG electrode will be prone to becoming dislodged.Notwithstanding the cause of electrode dislodgment, depending upon thetype of ECG monitor employed, precise re-placement of a dislodged ECGelectrode may be essential to ensuring signal capture at the samefidelity. Moreover, dislodgment may occur unbeknownst to the patient,making the ECG recordings worthless. Further, some patients may haveskin that is susceptible to itching or irritation, and the wearing ofECG electrodes can aggravate such skin conditions. Thus, a patient maywant or need to periodically remove or replace ECG electrodes during along-term ECG monitoring period, whether to replace a dislodgedelectrode, reestablish better adhesion, alleviate itching or irritation,allow for cleansing of the skin, allow for showering and exercise, orfor other purpose. Such replacement or slight alteration in electrodelocation actually facilitates the goal of recording the ECG signal forlong periods of time.

Conventionally, Holter monitors are widely used for long-term extendedECG monitoring. Typically, they are used for only 24-48 hours. A typicalHolter monitor is a wearable and portable version of an ECG that includecables for each electrode placed on the skin and a separatebattery-powered ECG recorder. The cable and electrode combination (orleads) are placed in the anterior thoracic region in a manner similar towhat is done with an in-clinic standard ECG machine. The duration of aHolter monitoring recording depends on the sensing and storagecapabilities of the monitor, as well as battery life. A “looping” Holtermonitor (or event) can operate for a longer period of time byoverwriting older ECG tracings, thence “recycling” storage in favor ofextended operation, yet at the risk of losing event data. Althoughcapable of extended ECG monitoring, Holter monitors are cumbersome,expensive and typically only available by medical prescription, whichlimits their usability. Further, the skill required to properly placethe electrodes on the patient's chest hinders or precludes a patientfrom replacing or removing the precordial leads and usually involvesmoving the patient from the physician office to a specialized centerwithin the hospital or clinic. Also, Holter monitors do not provideinformation about the patient's air flow, further limiting theirusefulness in diagnosing the patient.

The ZIO XT Patch and ZIO Event Card devices, manufactured by iRhythmTech., Inc., San Francisco, Calif., are wearable stick-on monitoringdevices that are typically worn on the upper left pectoral region torespectively provide continuous and looping ECG recording. The locationis used to simulate surgically implanted monitors. Both of these devicesare prescription-only and for single patient use. The ZIO XT Patchdevice is limited to a 14-day monitoring period, while the electrodesonly of the ZIO Event Card device can be worn for up to 30 days. The ZIOXT Patch device combines both electronic recordation components,including battery, and physical electrodes into a unitary assembly thatadheres to the patient's skin. The ZIO XT Patch device uses adhesivesufficiently strong to support the weight of both the monitor and theelectrodes over an extended period of time and to resist disadherancefrom the patient's body, albeit at the cost of disallowing removal orrelocation during the monitoring period. Moreover, throughoutmonitoring, the battery is continually depleted and battery capacity canpotentially limit overall monitoring duration. The ZIO Event Card deviceis a form of downsized Holter monitor with a recorder component thatmust be removed temporarily during baths or other activities that coulddamage the non-waterproof electronics. Both devices representcompromises between length of wear and quality of ECG monitoring,especially with respect to ease of long term use, female-friendly fit,and quality of atrial (P-wave) signals. Furthermore, both devices do notmonitor the patient's air flow, further limiting their usefulness indiagnosing the patient.

While portable devices that combine respiratory and cardiac monitoringexist, these devices are also generally inadequate for long-termmonitoring due to their inconvenience and restraint that they place onthe patient's movements. For example, SleepView monitor devices,manufactured by Cleveland Medical Devices Inc. of Cleveland, Ohio,require a patient to wear multiple sensors on the patient's body,including a belt on the patient's chest, a nasal cannula, and anoximetry sensor on the patient's finger, with these sensors beingconnected by tubing and wires to a recording device worn on the belt.Having to wear these sensors throughout the patient's body limits thepatient's mobility and may be embarrassing to the patient if worn inpublic, deterring the patient from undergoing such a monitoring for anextended period of time.

Therefore, a need remains for a self-contained personal air flow monitorcapable of recording both air flow data, other respiratory data such asrespiratory rate and effort, and ECG data, practicably capable of beingworn for a long period of time in both men and women, and capable ofrecording atrial signals reliably.

A further need remains for a device capable of recording signals idealfor arrhythmia discrimination, especially a device designed for atrialactivity recording, as the arrhythmias are coupled to the associatedpulmonary problems common to sleep apnea and other respiratorydisorders.

SUMMARY

Physiological monitoring can be provided through a wearable monitor thatincludes two components, a flexible extended wear electrode patch and aremovable reusable monitor recorder. The wearable monitor sits centrally(in the midline) on the patient's chest along the sternum orientedtop-to-bottom. The placement of the wearable monitor in a location atthe sternal midline (or immediately to either side of the sternum), withits unique narrow “hourglass”-like shape, benefits long-term extendedwear by removing the requirement that ECG electrodes be continuallyplaced in the same spots on the skin throughout the monitoring period.Instead, the patient is free to place an electrode patch anywhere withinthe general region of the sternum, the area most likely to record highquality atrial signals or P-waves. In addition, power is providedthrough a battery provided on the electrode patch, which avoids havingto either periodically open the housing of the monitor recorder for thebattery replacement, which also creates the potential for moistureintrusion and human error, or to recharge the battery, which canpotentially take the monitor recorder off line for hours at a time. Inaddition, the electrode patch is intended to be disposable, while themonitor recorder is a reusable component. Thus, each time that theelectrode patch is replaced, a fresh battery is provided for the use ofthe monitor recorder. The wearable monitor further includes an air flowsensor and air flow telemetry can be collected contemporaneously withECG data either with sensors contained on the underlying dermal patch orwith a hub-and-spoke configuration that allows for either a directsensor contact with the monitor or a wirelessly relayed transfer of airflow and pulmonary data to the central monitor.

One embodiment provides a monitor recorder optimized forelectrocardiography and respiratory data acquisition and processing. Therecorder includes a sealed housing adapted to be removably secured intoa non-conductive receptacle on a disposable extended wear electrodepatch and an electronic circuitry comprised within the sealed housing.The electronic circuitry includes an electrocardiographic front endcircuit electrically interfaced to an externally-poweredmicro-controller and operable to sense electrocardiographic signalsthrough electrodes provided on the disposable extended wear electrodepatch; the micro-controller operable to execute under micro programmablecontrol and interfaced to one or more respiratory sensors, themicro-controller further operable to sample the electrocardiographicsignals, to sample respiratory events detected by the one or morerespiratory sensors upon receiving one or more signals from the one ormore respiratory sensors, to buffer each of the respiratory eventsamples, to compress each of the buffered respiratory event samples, tobuffer each of the compressed respiratory event samples, and to writethe buffered compressed respiratory event samples and the samples of theelectrocardiography signals into an externally-powered flash memory; andthe externally-powered flash memory electrically interfaced with themicro-controller and operable to store samples of theelectrocardiographic signals and the respiratory events.

A further embodiment provides an electrocardiography and respiratorymonitoring patch. A pair of electrocardiographic electrodes arerespectively affixed to and conductively exposed on a contact surface ofeach end of a flexible backing to sense electrocardiographic data. Acircuit has a pair of circuit traces and each circuit trace originateswithin one of the ends of the flexible backing and is coupled to one ofthe electrocardiographic electrodes. A non-conductive receptacle isadhered on one end of the flexible backing opposite the contact surfaceand includes a battery. At least one respiratory sensor is positioned ona surface of the non-conductive receptacle facing the flexible backingand includes a strain gauge. The respiratory sensor is electricallyconnected to the battery and senses respiratory data.

A still further embodiment provides an electrocardiography andrespiration monitor. An electrocardiography patch includes a flexiblebacking and a pair of electrocardiographic electrodes respectivelyaffixed to and conductively exposed on a contact surface of each end ofthe flexible backing to sense electrocardiographic data. A circuitincludes a pair of circuit traces. Each circuit trace originates withinone of the ends of the flexible backing and is coupled to one of theelectrocardiographic electrodes. A non-conductive receptacle is adheredon one end of the flexible backing opposite the contact surface andincludes a battery. At least one respiratory sensor includes a straingauge and is positioned on a surface of the non-conductive receptaclefacing the flexible backing. The respiratory sensor is electricallyconnected to the battery and senses respiratory data. Anelectrocardiography monitor recorder includes a sealed housing shaped tobe removably attached to the electrocardiography patch and anexternally-powered micro-controller. An electrocardiographic front endcircuit is interfaced to the micro-controller and operable to sense theelectrocardiographic data.

The monitoring patch is especially suited to the female anatomy. Thenarrow longitudinal midsection can fit nicely within the intermammarycleft of the breasts without inducing discomfort, whereas conventionalpatch electrodes are wide and, if adhesed between the breasts, wouldcause chafing, irritation, frustration, and annoyance, leading to lowpatient compliance.

The foregoing aspects enhance ECG monitoring performance and qualityfacilitating long-term ECG recording, critical to accurate arrhythmiadiagnosis.

In addition, the foregoing aspects enhance comfort in women (and certainmen), but not irritation of the breasts, by placing the monitoring patchin the best location possible for optimizing the recording of cardiacsignals from the atrium, another feature critical to proper arrhythmiadiagnosis. And, such ECG recording systems can easily be interfaced withair flow and respiratory recording systems that can extend cephalad tothe sternum for recording tracheal airflow and for monitoringrespiratory rate and underlying dermal SpO₂ and pCO₂ measures, allfeatures of pulmonary disorders.

Finally, the foregoing aspects as relevant to monitoring are equallyapplicable to recording other physiological measures, such astemperature, respiratory rate, blood sugar, oxygen saturation, and bloodpressure, as well as other measures of body chemistry and physiology.

Still other embodiments will become readily apparent to those skilled inthe art from the following detailed description, wherein are describedembodiments by way of illustrating the best mode contemplated. As willbe realized, other and different embodiments are possible and theembodiments' several details are capable of modifications in variousobvious respects, all without departing from their spirit and the scope.Accordingly, the drawings and detailed description are to be regarded asillustrative in nature and not as restrictive.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are diagrams showing, by way of examples, a self-containedpersonal air flow sensing monitor, including a monitor recorder inaccordance with one embodiment, respectively fitted to the sternalregion of a female patient and a male patient.

FIG. 3 is a perspective view showing a system for remote interfacing ofa self-contained personal air flow sensing monitor in accordance withone embodiment inserted.

FIG. 4 is a perspective view showing an extended wear electrode patchwith the monitor recorder in accordance with one embodiment.

FIG. 5 is a perspective view showing the monitor recorder of FIG. 4.

FIG. 6 is a perspective view showing the extended wear electrode patchof FIG. 4 without a monitor recorder inserted.

FIG. 7 is an alternative view of the non-conductive receptacle 25 ofFIG. 6.

FIG. 8 is a bottom plan view of the monitor recorder of FIG. 4.

FIG. 9 is a top view showing the flexible circuit of the extended wearelectrode patch of FIG. 4 when mounted above the flexible backing.

FIG. 10 is a functional block diagram showing the component architectureof the circuitry of the monitor recorder of FIG. 4.

FIG. 11 is a functional block diagram showing the circuitry of theextended wear electrode patch of FIG. 4.

FIG. 12 is a flow diagram showing a monitor recorder-implemented methodfor monitoring ECG and air flow data for use in the monitor recorder ofFIG. 4.

FIG. 13 is a graph showing, by way of example, a typical ECG waveform.

FIG. 14 is a flow diagram showing a method for offloading and convertingECG and other physiological data from a self-contained air flow sensingmonitor in accordance with one embodiment.

FIG. 15 is a flow diagram showing method for processing data collectedby the self-contained personal air flow sensing monitor in accordancewith one embodiment.

FIG. 16 is a flow diagram showing a routine for identifying a type of anair flow event for use in the method of FIG. 15 in accordance with oneembodiment.

FIG. 17 is a diagram showing, by way of example, a self-containedpersonal air flow sensing monitor fitted to the sternal region of afemale patient in accordance with a further embodiment.

FIG. 18 is a perspective view showing the extended wear electrode patchwith an elongated tab in accordance with one embodiment without themonitor inserted in accordance with one embodiment.

FIG. 19 shows an alternative perspective view of the non-conductivereceptacle of FIG. 18 in accordance with one embodiment

DETAILED DESCRIPTION

Long-term collection of air flow telemetry contemporaneous withcollection of ECG data allows a physician interpreting physiologicalmonitoring results to correlate abnormal respiratory and cardiac events,helping the physician in diagnosing the patient. Results of such amonitoring can be particularly useful for diagnosing sleep apneaconditions, which have both respiratory and cardiac components. Forexample, obstructive sleep apnea (OSA) is a disorder characterized byphysical occlusion of upper airways during a patient's sleep, whichcauses either an apnea, a complete cessation of air flow, or a hypopnea,a partial cessation of air flow. An OSA episode causes the patient totransiently awaken to a lighter stage of sleep, the awakening followedby a restoration of the air flow. The occlusion causes a hypoxemia, anabnormal decrease in blood oxygen level, and is accompanied by strenuousrespiratory efforts, such as thoracoabdominal movements, of the patient.OSA episodes may further be accompanied by cardiac arrhythmias. Thehypoxemia is accompanied by a rise in peripheral sympathetic activity,which in turn may trigger a tachyarrhythmia once the patient'srespiration resumes. The sympathetic activity may remain at a heightenedlevel even during the patient's wakefulness, triggering furthertachyarrhythmias. Furthermore, in some patients, the hypoxemia can beaccompanied by cardiac parasympathetic activity, which can cause aprofound nocturnal bradycardia.

Central sleep apnea (CSA), which can be a form of Cheyne-Stokesbreathing, is similarly associated with cardiac abnormalities and hasbeen estimated to occur in 30-40% of patients with heart failure. CSA iscaused by a defect in central ventilatory control by the brain of thepatient; due to the defect, the brain fails to send respiratory commandsto the appropriate muscles, and the patient stops breathing. In contrastto OSA, the lack of respiratory commands results in respiratory effortsbeing absent during the OSA episode. As the patient stops breathingduring a CSA episode, the patient develops hypoxemia and hypercapnia, anabnormal increase in blood carbon dioxide levels; due to the risinghypoxemia and hypercarpnia, the brain reinitiates breathing, with thebreathing rate gradually rising until reaching the level of hyperpnea,abnormally deep breathing, which gradually ceases as the levels of bloodoxygen and carbon dioxide are restored to normal. The patient's heartrate rises gradually with the rise of the respiration rate, and thus,the hyperpnea may trigger a tachyarrhythmia. Monitoring both air flowand cardiac activity of the patient allows to correlate the cardiac andrespiratory abnormalities that OSA and CSA cause, and aid in diagnosingthese conditions.

Physiological monitoring can be provided through a wearable monitor thatincludes two components, a flexible extended wear electrode patch and aremovable reusable monitor recorder. FIGS. 1 and 2 are diagrams showing,by way of examples, a self-contained personal air flow sensing monitor12, including a monitor recorder 14 in accordance with one embodiment,respectively fitted to the sternal region of a female patient 10 and amale patient 11. The wearable monitor 12 sits centrally (in the midline)on the patient's chest along the sternum 13 oriented top-to-bottom withthe monitor recorder 14 preferably situated towards the patient's head.In a further embodiment, the orientation of the wearable monitor 12 canbe corrected post-monitoring, as further described infra. The electrodepatch 15 is shaped to fit comfortably and conformal to the contours ofthe patient's chest approximately centered on the sternal midline 16 (orimmediately to either side of the sternum 13). The distal end of theelectrode patch 15 extends towards the Xiphoid process and, dependingupon the patient's build, may straddle the region over the Xiphoidprocess. The proximal end of the electrode patch 15, located under themonitor recorder 14, is below the manubrium and, depending uponpatient's build, may straddle the region over the manubrium.

The placement of the wearable monitor 12 in a location at the sternalmidline 16 (or immediately to either side of the sternum 13)significantly improves the ability of the wearable monitor 12 tocutaneously sense cardiac electric signals, particularly the P-wave (oratrial activity) and, to a lesser extent, the QRS interval signals inthe ECG waveforms that indicate ventricular activity whilesimultaneously facilitating comfortable long-term wear for many weeks.The sternum 13 overlies the right atrium of the heart and the placementof the wearable monitor 12 in the region of the sternal midline 13 putsthe ECG electrodes of the electrode patch 15 in a location betteradapted to sensing and recording P-wave signals than other placementlocations, say, the upper left pectoral region or lateral thoracicregion or the limb leads. In addition, placing the lower or inferiorpole (ECG electrode) of the electrode patch 15 over (or near) theXiphoid process facilitates sensing of ventricular activity and providessuperior recordation of the QRS interval.

The monitor recorder 14 of the wearable air flow sensing monitor 12senses and records the patient's air flow and ECG data into an onboardmemory. In addition, the wearable monitor 12 can interoperate with otherdevices. FIG. 3 is a functional block diagram showing a system 120 forremote interfacing of a self-contained personal air flow sensing monitor12 in accordance with one embodiment. The monitor recorder 14 is areusable component that can be fitted during patient monitoring into anon-conductive receptacle provided on the electrode patch 15, as furtherdescribed infra with reference to FIG. 4, and later removed foroffloading of stored ECG data or to receive revised programming.Following completion of ECG and air flow monitoring, the monitorrecorder 14 can the monitor recorder 14 can then be connected to adownload station 125, which could be a programmer or other device thatpermits the retrieval of stored ECG monitoring data, execution ofdiagnostics on or programming of the monitor recorder 14, or performanceof other functions. The monitor recorder 14 has a set of electricalcontacts (not shown) that enable the monitor recorder 14 to physicallyinterface to a set of terminals 128 on a paired receptacle 127 of thedownload station 125. In turn, the download station 125 executes acommunications or offload program 126 (“Offload”) or similar programthat interacts with the monitor recorder 14 via the physical interfaceto retrieve the stored ECG monitoring data. The download station 125could be a server, personal computer, tablet or handheld computer, smartmobile device, or purpose-built programmer designed specific to the taskof interfacing with a monitor recorder 14. Still other forms of downloadstation 125 are possible.

Upon retrieving stored ECG monitoring data from a monitor recorder 14,middleware first operates on the retrieved data to adjust the ECGwaveform, as necessary, and to convert the retrieved data into a formatsuitable for use by third party post-monitoring analysis software, asfurther described infra with reference to FIG. 14. The formatted datacan then be retrieved from the download station 125 over a hard link 135using a control program 137 (“Ctl”) or analogous application executingon a personal computer 136 or other connectable computing device, via acommunications link (not shown), whether wired or wireless, or byphysical transfer of storage media (not shown). The personal computer136 or other connectable device may also execute middleware thatconverts ECG data and other information into a format suitable for useby a third-party post-monitoring analysis program, as further describedinfra with reference to FIG. 13. Note that formatted data stored on thepersonal computer 136 would have to be maintained and safeguarded in thesame manner as electronic medical records (EMRs) 134 in the securedatabase 124, as further discussed infra. In a further embodiment, thedownload station 125 is able to directly interface with other devicesover a computer communications network 121, which could be somecombination of a local area network and a wide area network, includingthe Internet, over a wired or wireless connection.

A client-server model could be used to employ a server 122 to remotelyinterface with the download station 125 over the network 121 andretrieve the formatted data or other information. The server 122executes a patient management program 123 (“Mgt”) or similar applicationthat stores the retrieved formatted data and other information in asecure database 124 cataloged in that patient's EMRs 134. In addition,the patient management program 123 could manage a subscription servicethat authorizes a monitor recorder 14 to operate for a set period oftime or under pre-defined operational parameters, such as described incommonly-assigned U.S. Pat. No. 9,655,538, issued May 23, 2017, thedisclosure of which is incorporated by reference.

The patient management program 123, or other trusted application, alsomaintains and safeguards the secure database 124 to limit access topatient EMRs 134 to only authorized parties for appropriate medical orother uses, such as mandated by state or federal law, such as under theHealth Insurance Portability and Accountability Act (HIPAA) or per theEuropean Union's Data Protection Directive. For example, a physician mayseek to review and evaluate his patient's ECG monitoring data, assecurely stored in the secure database 124. The physician would executean application program 130 (“Pgm”), such as a post-monitoring ECGanalysis program, on a personal computer 129 or other connectablecomputing device, and, through the application 130, coordinate access tohis patient's EMRs 134 with the patient management program 123. Otherschemes and safeguards to protect and maintain the integrity of patientEMRs 134 are possible.

During use, the electrode patch 15 is first adhesed to the skin alongthe sternal midline 16 (or immediately to either side of the sternum13). A monitor recorder 14 is then snapped into place on the electrodepatch 15 to initiate ECG monitoring. FIG. 4 is a perspective viewshowing an extended wear electrode patch 15 with a monitor recorder 14inserted in accordance with one embodiment. The body of the electrodepatch 15 is preferably constructed using a flexible backing 20 formed asan elongated strip 21 of wrap knit or similar stretchable material witha narrow longitudinal mid-section 23 evenly tapering inward from bothsides. A pair of cut-outs 22 between the distal and proximal ends of theelectrode patch 15 create a narrow longitudinal midsection 23 or“isthmus” and defines an elongated “hourglass”-like shape, when viewedfrom above. The electrode patch 15 incorporates features thatsignificantly improve wearability, performance, and patient comfortthroughout an extended monitoring period. During wear, the electrodepatch 15 is susceptible to pushing, pulling, and torqueing movements,including compressional and torsional forces when the patient bendsforward, and tensile and torsional forces when the patient leansbackwards. To counter these stress forces, the electrode patch 15incorporates strain and crimp reliefs, such as described incommonly-assigned U.S. Pat. No. 9,545,204, issued Jan. 17, 2017, thedisclosure of which is incorporated by reference. In addition, thecut-outs 22 and longitudinal midsection 23 help minimize interferencewith and discomfort to breast tissue, particularly in women (andgynecomastic men). The cut-outs 22 and longitudinal midsection 23further allow better conformity of the electrode patch 15 to sternalbowing and to the narrow isthmus of flat skin that can occur along thebottom of the intermammary cleft between the breasts, especially inbuxom women. The cut-outs 22 and longitudinal midsection 23 help theelectrode patch 15 fit nicely between a pair of female breasts in theintermammary cleft. Still other shapes, cut-outs and conformities to theelectrode patch 15 are possible. For example, an elongated tab mayextend from the flexible backing, as further described infra withreference to FIGS. 17-19.

The monitor recorder 14 removably and reusably snaps into anelectrically non-conductive receptacle 25 during use. The monitorrecorder 14 contains electronic circuitry for recording and storing thepatient's electrocardiography as sensed via a pair of ECG electrodesprovided on the electrode patch 15, such as described incommonly-assigned U.S. Pat. No. 9,730,593, issued Aug. 15, 2017, thedisclosure of which is incorporated by reference. The non-conductivereceptacle 25 is provided on the top surface of the flexible backing 20with a retention catch 26 and tension clip 27 molded into thenon-conductive receptacle 25 to conformably receive and securely holdthe monitor recorder 14 in place.

The monitor recorder 14 includes a sealed housing that snaps into placein the non-conductive receptacle 25. FIG. 5 is a perspective viewshowing the monitor recorder 14 of FIG. 4. The sealed housing 50 of themonitor recorder 14 intentionally has a rounded isoscelestrapezoidal-like shape 52, when viewed from above, such as described incommonly-assigned U.S. Design Pat. No. D717,955, issued on Nov. 18,2014, the disclosure of which is incorporated by reference. The edges 51along the top and bottom surfaces are rounded for patient comfort. Thesealed housing 50 is approximately 47 mm long, 23 mm wide at the widestpoint, and 7 mm high, excluding a patient-operable tactile-feedbackbutton 55. The sealed housing 50 can be molded out of polycarbonate,ABS, or an alloy of those two materials. The button 55 is waterproof andthe button's top outer surface is molded silicon rubber or similar softpliable material. A retention detent 53 and tension detent 54 are moldedalong the edges of the top surface of the housing 50 to respectivelyengage the retention catch 26 and the tension clip 27 molded intonon-conductive receptacle 25. Other shapes, features, and conformitiesof the sealed housing 50 are possible.

The electrode patch 15 is intended to be disposable. The monitorrecorder 14, however, is reusable and can be transferred to successiveelectrode patches 15 to ensure continuity of monitoring. The placementof the wearable monitor 12 in a location at the sternal midline 16 (orimmediately to either side of the sternum 13) benefits long-termextended wear by removing the requirement that ECG electrodes becontinually placed in the same spots on the skin throughout themonitoring period. Instead, the patient is free to place an electrodepatch 15 anywhere within the general region of the sternum 13.

As a result, at any point during ECG monitoring, the patient's skin isable to recover from the wearing of an electrode patch 15, whichincreases patient comfort and satisfaction, while the monitor recorder14 ensures ECG monitoring continuity with minimal effort. A monitorrecorder 14 is merely unsnapped from a worn out electrode patch 15, theworn out electrode patch 15 is removed from the skin, a new electrodepatch 15 is adhered to the skin, possibly in a new spot immediatelyadjacent to the earlier location, and the same monitor recorder 14 issnapped into the new electrode patch 15 to reinitiate and continue theECG monitoring.

During use, the electrode patch 15 is first adhered to the skin in thesternal region. FIG. 6 is a perspective view showing the extended wearelectrode patch 15 of FIG. 4 without a monitor recorder 14 inserted. Aflexible circuit 32 is adhered to each end of the flexible backing 20. Adistal circuit trace 33 and a proximal circuit trace (not shown)electrically couple ECG electrodes (not shown) to a pair of electricalpads 34. The electrical pads 34 are provided within a moisture-resistantseal 35 formed on the bottom surface of the non-conductive receptacle25. When the monitor recorder 14 is securely received into thenon-conductive receptacle 25, that is, snapped into place, theelectrical pads 34 interface to electrical contacts (not shown)protruding from the bottom surface of the monitor recorder 14, and themoisture-resistant seal 35 enables the monitor recorder 14 to be worn atall times, even during bathing or other activities that could expose themonitor recorder 14 to moisture.

In addition, a battery compartment 36 is formed on the bottom surface ofthe non-conductive receptacle 25, and a pair of battery leads (notshown) electrically interface the battery to another pair of theelectrical pads 34. The battery contained within the battery compartment35 can be replaceable, rechargeable or disposable.

The air flow monitor 12 can monitor a patient's physiology, includingboth the patient's air flow and ECG. FIG. 7 is an alternativeperspective view of the non-conductive receptacle 25 in accordance withone embodiment, showing an air flow sensor 42 included on the surface ofnon-conductive receptacle 25 that faces the flexible backing 20. The airflow sensor 42 includes a microphone that is positioned to detect soundsof breathing of the patient through the patient's sternum 13. Themicrophone may also be able to record sounds associated with thebreathing, such as snoring. The microphone can be aMicroElectrical-Mechanical System (MEMS) microphone, though other typesof microphones can be used in a further embodiment. In a furtherembodiment, the air flow sensor can be located in a different part ofthe electrode patch 15. In a still further embodiment, the air flowsensor 42 can be located on the monitor recorder 14. While the air flowsensor is shown to be the only component present on the surface of thenon-conductive receptacle, other components may also be present on thesurface. For example, an SPO2 sensor to measure blood oxygen level (notshown) can be included on the surface. In one embodiment, the SPO2sensor can include a reflectance pulse oximetry sensor; in a furtherembody ment, a transmissive pulse oximetry may be included as part ofthe SPO2 sensor. Similarly, a pCO₂ sensor (not shown) to measure bloodcarbon dioxide level may also be included on the surface. In addition, arespiratory rate sensor can be located on the surface of thenon-conductive receptacle 25. In one embodiment, the respiratory ratesensor can include a strain gauge, with parts of the strain gaugeextending beyond the material of the non-conductive receptacle 25 andthe flexible backing 20, and contacting the patient's skin. Therespiratory rate sensor can detect patient respiration and may furtherbe able to detect an amplitude of the chest movements during therespiration, which may assist in determining whether respiratory effortsare present during an apneic episode. In one embodiment, the parts ofthe gauge contacting the skin, the “arms,” may be adhered to the skin,making the gauge capable of detecting expansion and contraction of thepatient's chest as well as pauses between the chest movements. In afurther embodiment, the respiratory rate sensor can include atransthoracic impedance sensor. All of the sensors on the surface canalso be located in other parts of the patch 15.

While the self-contained air flow sensing monitor as shown in FIG. 4 iscapable of long-term collection of air flow and ECG data, the monitorcan be further modified for an improved air flow monitoring. Forexample, the extended wear patch may be further modified to provideimproved access to sounds of breathing in the patient's trachea. FIG. 17is a diagram showing, by way of example, a self-contained personal airflow sensing monitor 180 fitted to the sternal region of a femalepatient 10 in accordance with a further embodiment, with a modified,elongated extended wear electrode patch 181. The patch 181 includes anelongated tab 182, the tab 182 extending over the patient's sternalnotch 183. The extended tab 182 reaching over the sternal notch 183allows improved air flow telemetry detection, with an air flow sensorbeing placed over the sternal notch 13. This placement allows the airflow sensor to detect sounds from the trachea of the patient 10, whichmay provide improved quality of the air flow telemetry. The monitorrecorder 14 stores the recorded air flow telemetry as described supraand infra.

FIG. 18 is a perspective view showing the extended wear electrode patchwith an elongated tab in accordance with one embodiment without themonitor 14 inserted. The length and other dimensions of the extended tab182 may vary depending on the height of the patient and the tab 182 isof sufficient length to reach the patient's sternal notch 183. The tab182 can be made of the same material as the flexible backing 190, and bea continuous piece of stretchable material with the backing 190. Whileshown as having as widening towards a rounded proximal end, other shapesof the tab 182 are also possible. Still other shapes and configurationsof the tab 182 are possible.

An air flow sensor 191, which includes the microphone as describedabove, can be located near the proximal end of the tab 182, allowing thesensor 191 to detect tracheal breathing sounds through the sternal notch183. In a further embodiment, the air flow sensor can be located inanother part of the tab 182. Other sensors can also be located onextended tab 182, such as a respiratory rate sensor 192, SPO2 sensor193, and pCO₂ sensor 194. In the embodiment where the respiratory sensorincludes a strain gauge, the strain gauge may extend beyond thematerials of the tab 182, contacting the patient's skin, and allowingthe gauge to measure movements of the patient's chest. In a furtherembodiment, the other sensors may be collected at other parts of thepatch 181, as further described with reference to FIG. 19. The recordedtelemetry from the sensors can be transmitted to the electrical pads 195of the non-conductive receptacle 196 over wiring included in the patch180, allowing the monitor recorder 14 to receive the telemetry throughthe electric pads 195 once the monitor recorder is snapped into thenon-conductive receptacle 196. The sensors 191-195 can be electricallyconnected to the battery 197, or be powered from another source. In afurther embodiment, the sensors located on the extended tab 182 can beelectrically connected to a wireless transceiver (not shown), and cantransmit the recorded telemetry over the wireless transceiver to themonitor recorder 14. In the described embodiment, the extended tab 182can be at least partially covered with adhesive to facilitate theattachment of the patch to the sternal node. Similarly, the parts of therespiratory rate sensor contacting the patient's skin may further becovered with an adhesive. While the extended tab 182 can affect theplacement of sensors and the shape of the patch 181, unless otherwisementioned, configurations and characteristics of the embodiment of themonitor 180 can be the same as described above and below in regards tothe embodiment of the self-contained air flow sensing monitor shown withreference to FIG. 4, and the data collected by the embodiment of themonitor 180 can be processed in the same way as the data collected bythe embodiment of the monitor shown in FIG. 4.

As mentioned above, in the electrode patch shown in FIG. 18, respiratorysensors other than the air flow sensor 191 can be included either on theelongated tab 182 or on other parts of the patch 181. FIG. 19 shows analternative perspective view of the non-conductive receptacle 196 ofFIG. 18 in accordance with one embodiment, showing the surface of thenon-conductive receptacle 196 that faces the flexible backing 190. Therespiratory rate sensor 192, SPO2 sensor 193, and pCO₂ sensor 194 can belocated on the surface of the non-conductive receptacle, though otherlocations for these sensors are also possible. In the embodiment wherethe respiratory rate sensor 192 is a strain gauge, the arms of the gaugemay extend beyond the receptacle 196, contacting the patient's skin andallowing to the movement of the patient's chest.

The monitor recorder 14 draws power externally from the battery providedin the non-conductive receptacle 25, thereby uniquely obviating the needfor the monitor recorder 14 to carry a dedicated power source. FIG. 8 isa bottom plan view of the monitor recorder 14 of FIG. 4. A cavity 58 isformed on the bottom surface of the sealed housing 50 to accommodate theupward projection of the battery compartment 36 from the bottom surfaceof the non-conductive receptacle 25, when the monitor recorder 14 issecured in place on the non-conductive receptacle 25. A set ofelectrical contacts 56 protrude from the bottom surface of the sealedhousing 50 and are arranged in alignment with the electrical pads 34provided on the bottom surface of the non-conductive receptacle 25 toestablish electrical connections between the electrode patch 15 and themonitor recorder 14. In addition, a seal coupling 57 circumferentiallysurrounds the set of electrical contacts 56 and securely mates with themoisture-resistant seal 35 formed on the bottom surface of thenon-conductive receptacle 25. In the further embodiment where the airflow sensor 42 is located on the monitor recorder 14, the air flowsensor 42 can also be located on the bottom surface, though otherlocations are possible.

The placement of the flexible backing 20 on the sternal midline 16 (orimmediately to either side of the sternum 13) also helps to minimize theside-to-side movement of the wearable monitor 12 in the left- andright-handed directions during wear. To counter the dislodgment of theflexible backing 20 due to compressional and torsional forces, a layerof non-irritating adhesive, such as hydrocolloid, is provided at leastpartially on the underside, or contact, surface of the flexible backing20, but only on the distal end 30 and the proximal end 31. As a result,the underside, or contact surface of the longitudinal midsection 23 doesnot have an adhesive layer and remains free to move relative to theskin. Thus, the longitudinal midsection 23 forms a crimp relief thatrespectively facilitates compression and twisting of the flexiblebacking 20 in response to compressional and torsional forces. Otherforms of flexible backing crimp reliefs are possible.

Unlike the flexible backing 20, the flexible circuit 32 is only able tobend and cannot stretch in a planar direction. The flexible circuit 32can be provided either above or below the flexible backing 20. FIG. 9 isa top view showing the flexible circuit 32 of the extended wearelectrode patch 15 of FIG. 4 when mounted above the flexible backing 20.A distal ECG electrode 38 and proximal ECG electrode 39 are respectivelycoupled to the distal and proximal ends of the flexible circuit 32. Astrain relief 40 is defined in the flexible circuit 32 at a locationthat is partially underneath the battery compartment 36 when theflexible circuit 32 is affixed to the flexible backing 20. The strainrelief 40 is laterally extendable to counter dislodgment of the ECGelectrodes 38, 39 due to tensile and torsional forces. A pair of strainrelief cutouts 41 partially extend transversely from each opposite sideof the flexible circuit 32 and continue longitudinally towards eachother to define in ‘S’-shaped pattern, when viewed from above. Thestrain relief respectively facilitates longitudinal extension andtwisting of the flexible circuit 32 in response to tensile and torsionalforces. Other forms of circuit board strain relief are possible.

ECG monitoring and other functions performed by the monitor recorder 14are provided through a micro controlled architecture. FIG. 10 is afunctional block diagram showing the component architecture of thecircuitry 60 of the monitor recorder 14 of FIG. 4. The circuitry 60 isexternally powered through a battery provided in the non-conductivereceptacle 25 (shown in FIG. 6). Both power and raw ECG signals, whichoriginate in the pair of ECG electrodes 38, 39 (shown in FIG. 9) on thedistal and proximal ends of the electrode patch 15, are received throughan external connector 65 that mates with a corresponding physicalconnector on the electrode patch 15. The external connector 65 includesthe set of electrical contacts 56 that protrude from the bottom surfaceof the sealed housing 50 and which physically and electrically interfacewith the set of pads 34 provided on the bottom surface of thenon-conductive receptacle 25. The external connector includes electricalcontacts 56 for data download, microcontroller communications, power,analog inputs, and a peripheral expansion port. The arrangement of thepins on the electrical connector 65 of the monitor recorder 14 and thedevice into which the monitor recorder 14 is attached, whether anelectrode patch 15 or download station (not shown), follow the sameelectrical pin assignment convention to facilitate interoperability. Theexternal connector 65 also serves as a physical interface to a downloadstation 125 that permits the retrieval of stored ECG monitoring data,communication with the monitor recorder 14, and performance of otherfunctions.

Operation of the circuitry 60 of the monitor recorder 14 is managed by amicrocontroller 61. The micro-controller 61 includes a program memoryunit containing internal flash memory that is readable and writeable.The internal flash memory can also be programmed externally. Themicro-controller 61 draws power externally from the battery provided onthe electrode patch 15 via a pair of the electrical contacts 56. Themicrocontroller 61 connects to the ECG front end circuit 63 thatmeasures raw cutaneous electrical signals and generates an analog ECGsignal representative of the electrical activity of the patient's heartover time.

The circuitry 60 of the monitor recorder 14 also includes a flash memory62, which the micro-controller 61 uses for storing ECG monitoring dataand other physiology and information. The flash memory 62 also drawspower externally from the battery provided on the electrode patch 15 viaa pair of the electrical contacts 56. Data is stored in a serial flashmemory circuit, which supports read, erase and program operations over acommunications bus. The flash memory 62 enables the microcontroller 61to store digitized ECG data. The communications bus further enables theflash memory 62 to be directly accessed externally over the externalconnector 65 when the monitor recorder 14 is interfaced to a downloadstation.

The circuitry 60 of the monitor recorder 14 further includes anactigraphy sensor 64 implemented as a 3-axis accelerometer. Theaccelerometer may be configured to generate interrupt signals to themicrocontroller 61 by independent initial wake up and free fall events,as well as by device position. In addition, the actigraphy provided bythe accelerometer can be used during post-monitoring analysis to correctthe orientation of the monitor recorder 14 if, for instance, the monitorrecorder 14 has been inadvertently installed upside down, that is, withthe monitor recorder 14 oriented on the electrode patch 15 towards thepatient's feet, as well as for other event occurrence analyses, such asdescribed in commonly-assigned U.S. Pat. No. 9,739,224, issued Aug. 22,2017, the disclosure of which is incorporated by reference.

The microcontroller 61 includes an expansion port that also utilizes thecommunications bus. External devices, such as the air flow sensor 69,separately drawing power externally from the battery provided on theelectrode patch 15 or other source, can interface to the microcontroller61 over the expansion port in half duplex mode. For instance, anexternal physiology sensor can be provided as part of the circuitry 60of the monitor recorder 14, or can be provided on the electrode patch 15with communication with the micro-controller 61 provided over one of theelectrical contacts 56. The physiology sensor can include an SpO₂sensor, a pCO₂ sensor, blood pressure sensor, temperature sensor,glucose sensor, respiratory rate sensor, air flow sensor, volumetricpressure sensing, or other types of sensor or telemetric input sources.For instance, in the embodiment where the air flow sensor 69 is includedas part of the monitor recorder 14, the air flow sensor 69 isincorporated into the circuitry 60 and interfaces the micro-controller61 over the expansion port in half duplex, and may be configured togenerate interrupt signals to the microcontroller 61 when detecting anair flow event, as further discussed infra with reference to FIG. 12.Similarly, other respiratory sensors such as the SpO₂ sensor, a pCO₂sensor, and a respiratory rate sensor, can be connected to themicro-controller 61 in the same way and generate an interrupt signalupon detecting a respiratory event. In a further embodiment, a wirelessinterface for interfacing with other wearable (or implantable)physiology monitors, as well as data offload and programming, can beprovided as part of the circuitry 60 of the monitor recorder 14, or canbe provided on the electrode patch 15 with communication with themicro-controller 61 provided over one of the electrical contacts 56,such as described in commonly-assigned U.S. Pat. No. 9,433,367, issuedSep. 6, 2016, the disclosure of which is incorporated by reference.

Finally, the circuitry 60 of the monitor recorder 14 includespatient-interfaceable components, including a tactile feedback button66, which a patient can press to mark events or to perform otherfunctions, and a buzzer 67, such as a speaker, magnetic resonator orpiezoelectric buzzer. The buzzer 67 can be used by the microcontroller61 to output feedback to a patient such as to confirm power up andinitiation of ECG monitoring. Still other components as part of thecircuitry 60 of the monitor recorder 14 are possible.

While the monitor recorder 14 operates under micro control, most of theelectrical components of the electrode patch 15 operate passively. FIG.11 is a functional block diagram showing the circuitry 70 of theextended wear electrode patch 15 of FIG. 4. The circuitry 70 of theelectrode patch 15 is electrically coupled with the circuitry 60 of themonitor recorder 14 through an external connector 74. The externalconnector 74 is terminated through the set of pads 34 provided on thebottom of the non-conductive receptacle 25, which electrically mate tocorresponding electrical contacts 56 protruding from the bottom surfaceof the sealed housing 50 to electrically interface the monitor recorder14 to the electrode patch 15.

The circuitry 70 of the electrode patch 15 performs three primaryfunctions. First, a battery 71 is provided in a battery compartmentformed on the bottom surface of the non-conductive receptacle 25. Thebattery 71 is electrically interfaced to the circuitry 60 of the monitorrecorder 14 as a source of external power. The unique provisioning ofthe battery 71 on the electrode patch 15 provides several advantages.First, the locating of the battery 71 physically on the electrode patch15 lowers the center of gravity of the overall wearable monitor 12 andthereby helps to minimize shear forces and the effects of movements ofthe patient and clothing. Moreover, the housing 50 of the monitorrecorder 14 is sealed against moisture and providing power externallyavoids having to either periodically open the housing 50 for the batteryreplacement, which also creates the potential for moisture intrusion andhuman error, or to recharge the battery, which can potentially take themonitor recorder 14 off line for hours at a time. In addition, theelectrode patch 15 is intended to be disposable, while the monitorrecorder 14 is a reusable component. Each time that the electrode patch15 is replaced, a fresh battery is provided for the use of the monitorrecorder 14, which enhances ECG monitoring performance, quality, andduration of use. Finally, the architecture of the monitor recorder 14 isopen, in that other physiology sensors or components can be added byvirtue of the expansion port of the microcontroller 61. Requiring thoseadditional sensors or components to draw power from a source external tothe monitor recorder 14 keeps power considerations independent of themonitor recorder 14. Thus, a battery of higher capacity could beintroduced when needed to support the additional sensors or componentswithout effecting the monitor recorders circuitry 60.

In the embodiment where the air flow sensor 75 is a part of theelectrode patch 15, the air flow sensor 75 is included as a part of thecircuitry 70 and can draw power from the battery 71. In this embodiment,the air flow sensor 75 is connected to the external connector 74, andmay be configured to generate interrupt signals to the microcontroller61 when detecting an air flow event, as further discussed infra withreference to FIG. 12. Other respiratory sensors, such as the SpO₂sensor, the pCO₂ sensor, and the respiratory rate sensor can be includedas part of the circuitry 70 in the same manner as the air flow sensor69.

Second, the pair of ECG electrodes 38, 39 respectively provided on thedistal and proximal ends of the flexible circuit 32 are electricallycoupled to the set of pads 34 provided on the bottom of thenon-conductive receptacle 25 by way of their respective circuit traces33, 37. The signal ECG electrode 39 includes a protection circuit 72,which is an inline resistor that protects the patient from excessiveleakage current.

Last, in a further embodiment, the circuitry 70 of the electrode patch15 includes a cryptographic circuit 73 to authenticate an electrodepatch 15 for use with a monitor recorder 14. The cryptographic circuit73 includes a device capable of secure authentication and validation.The cryptographic device 73 ensures that only genuine, non-expired,safe, and authenticated electrode patches 15 are permitted to providemonitoring data to a monitor recorder 14, such as described incommonly-assigned U.S. Pat. No. 9,655,538, issued May 23, 2017, thedisclosure which is incorporated by reference.

The monitor recorder 14 continuously monitors the patient's heart rateand physiology. FIG. 12 is a flow diagram showing a monitorrecorder-implemented method 100 for monitoring ECG and air flow data foruse in the monitor recorder 14 of FIG. 4. Initially, upon beingconnected to the set of pads 34 provided with the non-conductivereceptacle 25 when the monitor recorder 14 is snapped into place, themicrocontroller 61 executes a power up sequence (step 101). During thepower up sequence, the voltage of the battery 71 is checked, the stateof the flash memory 62 is confirmed, both in terms of operability checkand available capacity, and microcontroller operation is diagnosticallyconfirmed. In a further embodiment, an authentication procedure betweenthe microcontroller 61 and the electrode patch 15 are also performed.

Following satisfactory completion of the power up sequence, an iterativeprocessing loop (steps 102-109) is continually executed by themicrocontroller 61. During each iteration (step 102) of the processingloop, the ECG frontend 63 (shown in FIG. 10) continually senses thecutaneous ECG electrical signals (step 103) via the ECG electrodes 38,29 and is optimized to maintain the integrity of the P-wave. A sample ofthe ECG signal is read (step 104) by the microcontroller 61 by samplingthe analog ECG signal output front end 63. FIG. 12 is a graph showing,by way of example, a typical ECG waveform 110. The x-axis representstime in approximate units of tenths of a second. The y-axis representscutaneous electrical signal strength in approximate units of millivolts.The P-wave 111 has a smooth, normally upward, that is, positive,waveform that indicates atrial depolarization. The QRS complex usuallybegins with the downward deflection of a Q wave 112, followed by alarger upward deflection of an R-wave 113, and terminated with adownward waveform of the S wave 114, collectively representative ofventricular depolarization. The T wave 115 is normally a modest upwardwaveform, representative of ventricular depolarization, while the U wave116, often not directly observable, indicates the recovery period of thePurkinje conduction fibers.

Sampling of the R-to-R interval enables heart rate informationderivation. For instance, the R-to-R interval represents the ventricularrate and rhythm, while the P-to-P interval represents the atrial rateand rhythm. Importantly, the PR interval is indicative ofatrioventricular (AV) conduction time and abnormalities in the PRinterval can reveal underlying heart disorders, thus representinganother reason why the P-wave quality achievable by the self-containedpersonal air flow sensing monitor described herein is medically uniqueand important. The long-term observation of these ECG indicia, asprovided through extended wear of the wearable monitor 12, providesvaluable insights to the patient's cardiac function and overallwell-being.

Each sampled ECG signal, in quantized and digitized form, is temporarilystaged in buffer (step 105), pending compression preparatory to storagein the flash memory 62 (step 106). Following compression, the compressedECG digitized sample is again buffered (step 107), then written to theflash memory 62 (step 108) using the communications bus. Processingcontinues (step 109), so long as the monitoring recorder 14 remainsconnected to the electrode patch 15 (and storage space remains availablein the flash memory 62), after which the processing loop is exited andexecution terminates. Still other operations and steps are possible.

The monitor recorder 14 also receives data from the air flow sensor 42.The data is received in a conceptually-separate execution thread as partof the iterative processing loop (steps 102-109) continually executed bythe microcontroller 61. Patient's air flow is monitored by the air flowsensor 42, and the air flow sensor 42 determines presence of an air flowevent, an air flow abnormality potentially indicative of a medicalcondition, that needs to be recorded as part of the monitoring (step140). The abnormalities in air flow to be recorded include bothinterruptions of airflow, such as apneas and hypopneas, as wellincreased air flow due to, for example, deepening of the patient'sbreathing during a hyperpnea. The presence of the interruption of airflow can be detected by either a complete lack of a sound of breathing,or, for a partial interruption, by a weakening below a certain thresholdof a strength of the sound signal detected. Similarly, when thefrequency of breathing sounds becomes greater than a predefinedthreshold, an increased air flow can be detected. Other techniques todetect air flow abnormalities can be used. If the duration of an airflow abnormality exceeds a temporal threshold, the abnormality isdetermined to be an air flow event (step 140). The temporal thresholdcan be 10 seconds, which is the length at which an air flow interruptionis classified as an apnea or a hypopnea, though other temporalthresholds can be used. If no abnormalities are detected or they do notrise to a level of an air flow event (step 140), the method 100 proceedsto step 109. A detection of an air flow event (140) causes the air flowsignal to generate an interrupt signal to the microcontroller 61,triggering further processing of the event as described below. Duringeach iteration (step 102) of the processing loop, if air flow event datais detected (step 140), a sample of the air flow telemetry is read (step141) by the microcontroller 61 and, if necessary, converted into adigital signal by the onboard ADC of the microcontroller 61. Each airflow event data sample, in quantized and digitized form, is temporarilystaged in buffer (step 142), pending compression preparatory to storagein the flash memory subsystem 62 (step 143). Following compression, thecompressed air flow data sample is again buffered (step 144), thenwritten to the flash memory 62 (step 145) using the communications bus.Processing continues (step 109), so long as the monitoring recorder 14remains connected to the electrode patch 15 (and storage space remainsavailable in the flash memory 62), after which the processing loop isexited and execution terminates. Still other operations and steps arepossible.

While the method 100 is described with reference to detecting an airflow event, abnormal physiological events detected by other respiratorysensors, such as the respiratory rate sensor 192, SpO₂ sensor 193, andpCO₂ sensor 194 can be recorded using similar steps. For example, arespiratory rate sensor would detect a respiratory rate event upon therate of respiration, or the amplitude of movement of the patient's chestduring the patient's respiration, rising above or falling below acertain threshold for a certain duration of time. An oxygen level eventcan be determined upon the patient's blood oxygen level as measured bythe SpO₂ 193 sensor rising above or falling below a certain threshold.Similarly, a carbon dioxide level event can be determined upon thecarbon dioxide level as measured by the pCO₂ 194 sensor rising above orfalling below a certain threshold. Upon the event detection, the eventwould be processed as described with regards to air flow 141-145 mutatismutandis. Respiratory events collected by these additional respiratorysensors, the respiratory rate sensor 192, the SpO₂ sensor 193, and thepCO₂ sensor 194, further aid a physician interpreting monitoring resultsin diagnosing an abnormal condition.

The monitor recorder 14 stores ECG data and other information in theflash memory subsystem 62 (shown in FIG. 10) using a proprietary formatthat includes data compression. As a result, data retrieved from amonitor recorder 14 must first be converted into a format suitable foruse by third party post-monitoring analysis software. FIG. 14 is a flowdiagram showing a method 150 for remote interfacing of a self-containedpersonal air flow sensing monitor 12 in accordance with one embodiment.The method 150 can be implemented in software and execution of thesoftware can be performed on a download station 125, which could be aprogrammer or other device, or a computer system, including a server 122or personal computer 129, such as further described supra with referenceto FIG. 3, as a series of process or method modules or steps. Forconvenience, the method 150 will be described in the context of beingperformed by a personal computer 136 or other connectable computingdevice (shown in FIG. 3) as middleware that converts ECG data and otherinformation into a format suitable for use by a third-partypost-monitoring analysis program. Execution of the method 150 by acomputer system would be analogous mutatis mutandis.

Initially, the download station 125 is connected to the monitor recorder14 (step 151), such as by physically interfacing to a set of terminals128 on a paired receptacle 127 or by wireless connection, if available.The data stored on by the monitor recorder 14, including ECG andphysiological monitoring data, other recorded data, and otherinformation are retrieved (step 152) over a hard link 135 using acontrol program 137 (“Ctl”) or analogous application executing on apersonal computer 136 or other connectable computing device. The dataretrieved from the monitor recorder 14 is in a proprietary storageformat and each datum of recorded ECG monitoring data, as well as anyother physiological data or other information, must be converted, sothat the data can be used by a third-party post-monitoring analysisprogram. Each datum of ECG monitoring data is converted by themiddleware (steps 153-159) in an iterative processing loop. During eachiteration (step 153), the ECG datum is read (step 154) and, ifnecessary, the gain of the ECG signal is adjusted (step 155) tocompensate, for instance, for relocation or replacement of the electrodepatch 15 during the monitoring period. In addition, depending upon theconfiguration of the wearable monitor 12, other physiological data (orother information), including patient events, such as air flow events,fall, peak activity level, sleep detection, detection of patientactivity levels and states and so on, may be recorded along with the ECGmonitoring data is read (step 156) and is time-correlated to the ECGmonitoring data (step 157). For instance, air flow events recorded bythe air flow events recorded by the air flow sensor 42 would betemporally matched to the ECG data to provide the proper physiologicalcontext to the sensed event occurrence. Similarly, actigraphy data mayhave been sampled by the actigraphy sensor 64 based on a sensed eventoccurrence, such as a sudden change in orientation due to the patienttaking a fall. In response, the monitor recorder 14 will embed theactigraphy data samples into the stream of data, including ECGmonitoring data, that is recorded to the flash memory 62 by themicro-controller 61. Post-monitoring, the actigraphy data is temporallymatched to the ECG data to provide the proper physiological context tothe sensed event occurrence. As a result, the three-axis actigraphysignal is turned into an actionable event occurrence that is provided,through conversion by the middleware, to third party post-monitoringanalysis programs, along with the ECG recordings contemporaneous to theevent occurrence. Other types of processing of the other physiologicaldata (or other information) are possible.

Thus, during execution of the middleware, any other physiological data(or other information) that has been embedded into the recorded ECGmonitoring data is read (step 156) and time-correlated to the time frameof the ECG signals that occurred at the time that the otherphysiological data (or other information) was noted (step 157). Finally,the ECG datum, signal gain adjusted, if appropriate, and otherphysiological data as time correlated are stored in a format suitable tothe backend software (step 158) used in post-monitoring analysis.

In a further embodiment, the other physiological data, if apropos, isembedded within an unused ECG track. For example, the SCP-ENG standardallows multiple ECG channels to be recorded into a single ECG record.The monitor recorder 14, though, only senses one ECG channel. The otherphysiological data can be stored into an additional ECG channel, whichwould otherwise be zero-padded or altogether omitted. The backendsoftware would then be able to read the other physiological data incontext with the single channel of ECG monitoring data recorded by themonitor recorder 14, provided the backend software implemented changesnecessary to interpret the other physiological data. Still other formsof embedding of the other physiological data with formatted ECGmonitoring data, or of providing the other physiological data in aseparate manner, are possible.

Processing continues (step 159) for each remaining ECG datum, afterwhich the processing loop is exited and execution terminates. Stillother operations and steps are possible.

The collection of the ECG data as described above, and as described in acommonly assigned U.S. Pat. No. 9,730,593, issued Aug. 15, 2017, thedisclosure of which is incorporated by reference, allows acquisition ofECG data collected over an extended period of time, and when combinedthe recording of air flow events, simplifies monitoring for episodes ofcardiorespiratory conditions. The data collected by the monitor 12 anddownloaded to the download station 125 can be further processed by theapplication software 130 to correlate the air flow events with ECG andother non-air flow data physiological data, which can be helpful to aphysician in diagnosing the patient. FIG. 15 is a flow diagram showingthe method 160 for processing data collected by the self-containedpersonal air flow sensing monitor 12 in accordance with one embodiment.Physiological data that includes the identified air flow events, andnon-air flow data, including the ECG data and, if applicable, datacollected by other sensors of the monitor 12, is received by theapplication software 130 (step 161). The non-air flow physiological datacollected approximately concurrently to the airflow events is identified(step 162). The approximately concurrent data can include not only datathat was collected at the same time as when the air flow events tookplace, but also data collected within a specified time interval from abeginning or an end of each of the air flow events. Optionally, theidentified concurrent data can be processed to detect otherphysiological events, such as cardiac arrhythmias, approximatelycontemporaneous to air flow events (step 163). For example, the sampledECG signals can be processed to identify a presence of a cardiacarrhythmia that is substantially contemporaneous to the air flow events.For example, a heart rate in excess of 100 beats per minute (bpm) canindicate a tachyarrhythmia, and temporal intervals where the heart rateexceeds the 100 bpm threshold can be marked as an event indicative of atachyarrhythmia. Similarly, a heart rate falling below 60 bpm can beindicative of a bradyarrhythmia, and temporal intervals where thepatient's heart rate exceeds 60 bpm can be marked as events indicativeof a bradyarrhythmia. Similarly, the substantially contemporaneousactigraphy data can also be processed to detect actigraphy events, asfurther described in detail in commonly-assigned U.S. Pat. No.9,737,224, issued Aug. 22, 2017, the disclosure of which is incorporatedby reference. Other ways to process the non-air flow data are possible.The occurrence of arrhythmias concurrent with respiratory problems canindicate the diagnosis of serious sleep apnea. While the method 160 isdescribed with reference to processing data from a monitoring that hasalready concluded, in a further embodiment, the processing can beperformed on the air flow monitor 12, and the occurrence of arrhythmiasconcurrent with respiratory problems can also serve as a source ofinitiating an alarm system for patient awareness and alerting thepatient with an auditory alert or vibratory alert on the monitor itself,such as through the use of the buzzer 67.

Following the optional identification of the contemporaneous data, thetype of the air flow event can be detected (step 164), as furtherdescribed with reference to FIG. 16. Finally, the information about theair flow events and approximately concurrent non-air flow data is outputto a user, such as a physician, such as though a screen of a personalcomputer 129 (step 165). The output information can include the time theevents occurred, the duration of the events, the nature of the event(interruption of air flow or an increased air flow), the magnitude ofthe air flow abnormality during the event, the type of the event, aswell as information about the identified concurrent non-air flowphysiological data. In a further embodiment, the sounds recorded duringthe events, such as snoring can also be output. Any events identifiedbased on the non-air flow data can also be output to the user. In afurther embodiment, non-air flow physiological data that is notsubstantially contemporaneous to the air flow events is also output tothe user.

Identification of a type of an air flow event can provide further helpto the physician interpreting the results in diagnosing the patient.FIG. 16 is a flow diagram showing a routine 170 for identifying a typeof an air flow event for use in the method 160 of FIG. 15. As sleepapnea air flow events occur during a patient's sleep or upon awakening,when respiration resumes, whether the patient was asleep during orimmediately prior to an air flow event is important to diagnosing sleepapnea. Whether the patient was asleep approximately concurrently to anair flow event, which includes the period of time during the event or ina predefined temporal interval before the event, is determined by theapplication software 130 (step 171). The determination can be made usingthe data collected by the actigraphy sensor 64, which monitors thepatient's posture and movement rate. When the actigraphy sensor 64 datashows that the patient assumed a recumbent position and the patient'smovement rate has fallen below a predefined threshold, the applicationsoftware 130 can determine that the patient has fallen asleep. Otherphysiological data can also be used to determine if the patient isasleep. For example, falling asleep is characterized by a gradualdecrease of the patient's heart rate. By obtaining an average of theheart rate of the patient when the patient is awake, either by analyzingthe ECG data and other physiological data collected during themonitoring or from another source, the application software 130 can marka gradual decline in heart rate from that level as the patient fallingasleep. Other ways to determine whether the patient is asleep arepossible. If the event occurs when the patient is not asleep and has notbeen within the predefined temporal period before the event (step 171),the event is determined as not indicative of a sleep apnea condition(step 172), and the routine 170 ends. If the patient is asleep duringthe event (step 171), the application software 130 determines the eventto be indicative of a sleep apnea condition (step 173). The applicationfurther determines whether respiratory efforts are associated with theevent (step 174). For apneic or hypopneic events, the association ispresent when the event is accompanied by respiratory efforts. Forhyperpneic events, the association is present when the hyperpneic eventwas preceded within a predefined time interval by an apneic or hypopneicevent accompanied by respiratory efforts. The presence of respiratoryefforts can be determined using the data collected the respiratory ratesensor 192 or the actigraphy sensor 64, with the presence of chestmovements during an air flow event being indicative of respiratoryefforts. In a further embodiment, the respiratory efforts can bedetected based on data collected by an impedance pneumograph included asone of the physiological sensors of the monitor 12, which can detectchest movements. Other ways to determine the presence of the respiratoryefforts are possible.

If the respiratory efforts are associated with the event (step 174), theapplication determines the event type to be indicative of an OSAcondition (step 175), terminating the routine 170. If the respiratoryefforts are not associated with the event (step 176), the applicationdetermines the event to be indicative of a CSA condition (step 175),terminating the routine 150. While the routine 170 is described inrelation to a sleep apnea condition, in a further embodiment, theapplication software can be used to identify other types of respiratoryevents.

While the invention has been particularly shown and described asreferenced to the embodiments thereof, those skilled in the art willunderstand that the foregoing and other changes in form and detail maybe made therein without departing from the spirit and scope.

What is claimed is:
 1. An electrocardiography and respiratory monitoringpatch, comprising: a flexible backing; a pair of electrocardiographicelectrodes respectively affixed to and conductively exposed on a contactsurface of each end of the flexible backing to senseelectrocardiographic data; a circuit comprising a pair of circuittraces, each circuit trace originating within one of the ends of theflexible backing and coupled to one of the electrocardiographicelectrodes; a non-conductive receptacle adhered on one end of theflexible backing opposite the contact surface and comprising a batteryand a plurality of electrical pads, wherein a pair of the electricalpads is coupled with the pair of circuit traces; and at least onerespiratory sensor comprising a strain gauge and positioned on a surfaceof the non-conductive receptacle facing the flexible backing, whereinthe respiratory sensor is electrically connected to the battery andsenses respiratory data and at least a part of the strain gauge extendsbeyond the non-conductive receptacle and the flexible backing to contacta patient's skin.
 2. An electrocardiography and respiratory monitoringpatch according to claim 1, wherein the strain gauge that extends beyondthe non-conductive receptacle and the flexible backing comprises armsthat contact skin of a patient on which the flexible backing is adhered.3. An electrocardiography and respiratory monitoring patch according toclaim 1, wherein the strain gauge detects expansion and contraction of apatient's chest on which the flexible backing is adhered.
 4. Anelectrocardiography and respiratory monitoring patch according to claim1, wherein the respiratory sensor comprises a transthoracic impedancesensor.
 5. An electrocardiography and respiratory monitoring patchaccording to claim 1, wherein the respiratory sensor transmits therespiratory data over a wireless transceiver or via wires.
 6. Anelectrocardiography and respiratory monitoring patch according to claim1, further comprising: a further respiratory sensor positioned on thesurface of the non-conductive receptacle facing the flexible backingadjacent to the respiratory sensor.
 7. An electrocardiography andrespiratory monitoring patch according to claim 1, wherein at least onerespiratory event is identified from the respiratory data.
 8. Anelectrocardiography and respiratory monitoring patch according to claim7, wherein the electrocardiographic data occurring concurrent to therespiratory event is utilized to identify a type of the respiratoryevent.
 9. An electrocardiography and respiratory monitoring patchaccording to claim 1, further comprising: a microphone positioned on theflexible backing to detect sounds of breathing.
 10. Anelectrocardiography and respiration monitor, comprising: a flexiblebacking; a pair of electrocardiographic electrodes respectively affixedto and conductively exposed on a contact surface of each end of theflexible backing to sense electrocardiographic data; a circuitcomprising a pair of circuit traces, each circuit trace originatingwithin one of the ends of the flexible backing and coupled to one of theelectrocardiographic electrodes; a non-conductive receptacle adhered onone end of the flexible backing opposite the contact surface andcomprising a battery and a plurality of electrical pads, wherein a pairof the electrical pads is coupled with the pair of circuit traces; andat least one respiratory sensor comprising a strain gauge and positionedon a surface of the non-conductive receptacle facing the flexiblebacking, wherein the respiratory sensor is electrically connected to thebattery and senses respiratory data and at least a part of the straingauge extends beyond the non-conductive receptacle and the flexiblebacking to contact a patient's skin; and an electrocardiography monitorrecorder, comprising: a sealed housing shaped to be removably attachedto the electrocardiography patch; an externally-poweredmicro-controller; and an electrocardiographic front end circuitinterfaced to the micro-controller and operable to sense theelectrocardiographic data.
 11. An electrocardiography and respiratorymonitor according to claim 10, wherein the strain gauge that extendsbeyond the non-conductive receptacle and the flexible backing comprisesarms that contact skin of a patient on which the flexible backing isadhered.
 12. An electrocardiography and respiratory monitor according toclaim 10, wherein the strain gauge detects expansion and contraction ofa patient's chest on which the flexible backing is adhered.
 13. Anelectrocardiography and respiratory monitor according to claim 10,wherein the respiratory sensor comprises a transthoracic impedancesensor.
 14. An electrocardiography and respiratory monitor according toclaim 10, wherein the respiratory sensor transmits the respiratory dataover a wireless transceiver or via wires.
 15. An electrocardiography andrespiratory monitor according to claim 10, further comprising: a furtherrespiratory sensor positioned on the surface of the non-conductivereceptacle facing the flexible backing adjacent to the respiratorysensor.
 16. An electrocardiography and respiratory monitor according toclaim 10, wherein at least one respiratory event is identified from therespiratory data.
 17. An electrocardiography and respiratory monitoraccording to claim 16, wherein the electrocardiographic data occurringconcurrent to the respiratory event is utilized to identify a type ofthe respiratory event.
 18. An electrocardiography and respiratorymonitor according to claim 10, further comprising: a microphonepositioned on the flexible backing to detect sounds of breathing.